Please cite both the liureg related paper and the liureg package: To cite liureg article in publications use:

Imdad, M. U. & Aslam, M. (2018). liureg: Liu Regression with Liu Biasing Parameters and Statistics. URL https://CRAN.R-project.org/package=liureg, R package version 1.1.2

Imdadullah, M., Aslam, M., and Altaf, S., (2017). liureg: A Comprehensive R Package for the Liu Estimation of Linear Regression Model with Collinear Regressors. The R Journal, 9(2), 232--247 https://journal.r-project.org/archive/2017/RJ-2017-048/index.html

Corresponding BibTeX entries:

  @Manual{,
    title = {{liureg}: Liu Regression with Liu Biasing Parameters and
      Statistics},
    author = {M. U. Imdad and M. Aslam},
    year = {2018},
    note = {R package version 1.1.2},
    url = {https://CRAN.R-project.org/package=liureg},
  }

  @Article{,
    title = {liureg: A Comprehensive R Package for the Liu Estimation
      of Linear Regression Model with Collinear Regressors},
    author = {M. Imdadullah and M. Aslam},
    journal = {The R Journal},
    year = {2017},
    volume = {9(2)},
    pages = {232-247},
    url =
      {https://journal.r-project.org/archive/2017/RJ-2017-048/index.html},
  }